Grounding wire connector



NOV. 3, 1970 R s w, JR 3,538,239

GROUNDING WIRE CONNECTOR Filed Dec. 26, 1968 I INVENTOR. FLOYD HAROLD RENSHAW, JR.

United States Patent Office 3,538,239 Patented Nov. 3, 1970 3,538,239 GROUNDING WIRE CONNECTOR Floyd Harold Renshaw, Jr., Hershey, Pa., assignor to AMP Incorporated, Harrisburg, Pa. Filed Dec. 26, 1968, Ser. No. 787,140 Int. Cl. H02g 15/08 US. Cl. 174--75 7 Claims ABSTRACT OF THE DISCLOSURE This invention relates to improved electrical connectors for use in conjunction with shielded wire or caxial cable of the type having a center conductor surrounded by subsequent layers of insulation and conductive braid.

In some radio frequency applications, it is desirable to terminate the outer conductive braid of shielded wire to ground means. In these applications, it is desirable to crimp the braid to a coupling element or connector in such a manner that the insulation and center conductor continue unbroken through the coupling element to an electrical element. Ground wire means sandwiched in the coupling element couples the braid to ground means.

Prior similar connectors for this purpose are shown and described in US. Pat. No. 2,890,267, which is assigned to the present assignee. These prior connectors have inner ferrules surrounded by and spaced from outer ferrules, however, they are difficult to make and use. They are sometimes made in several pieces, and subsequently assembled into one piece. Also they are made in loose piece form, it is extremely difficult or impossible to feed them into automatic crimping presses and it is difiicult to position the braid between the ferrules. For these and other reasons, prior connectors are considered to be expensive.

It is an object of the present invention to provide a new, improved and inexpensive connector means for terminating the conductive braid of shielded wire or c0- axial cable.

Another object is to provide connector means having inner ferrule means and outer ferrule means which are spaced from each other, but which are connected to each other by a strap of metal.

A further object is to provide improved connector means with lead-in means thereon by which the shield of a wire may be easily entered into place in the connector.

An additional object is to provide inspection means in a connector to assure proper location of a wire in the connector before and after crimping.

A still further object is to provide gripping means on the outer ferrule of a connector to grip and hold the outer conductor of shielded wire upon crimping, and support means on the inner ferrule of the connector to prevent undue compression damage to the center conductor and insulation of the wire.

Still another object is to provide stop means in a connector by which the end of a wire shield is properly located within the connector.

Other objects and attainments of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings in which there is shown and described an illustrative embodiment of the invention; it is to be understood, however, that this embodiment is not intended to be exhaustive nor limiting of the invention but is given for purposes of illustration in order that others skilled in the art may fully understand the invention and the principles thereof and the manner of applying it in practical use so that they may modify it in various forms, each as may be best suited to the conditions of a particular use.

In the drawings:

FIG. 1 is a perspective view of a connector according to this invention;

FIG. 2 is a perspective view of a connection to shielded wire;

FIG. 3 is a sectional view taken through the lines 3-3 of FIG. 1; and

FIG. 4 is a sectional view taken through the lines 4-4 of FIG. 2.

Referring first to FIGS. l-4, a shielded wire A and a grounding wire B are interconnected by a connector C. The wire A has a central conductor 2, surrounded by a layer of insulation 4, which in turn is surrounded by a braided outer conductor 6. Wire A can either be shielded wire or coaxial cable. The connector C consists of an inner round ferrule 8 and an outer U-shaped ferrule 10 which are integrally connected by a strap 12. The connector C is made from electrically conductive sheet metal, such as brass, and is blanked and formed by conventional metal-stamping and metal-forming techniques. Connec tors C may be made and connected together via strip S so as to be in strip form so that the connectors may be easily handled and stored. Individual connectors C may be cut from the strip S by an automatic crimping press when they are crimped to wires. Alternatively, the connectors may be cut from the strip S and subsequently crimped to wires by hand-crimping tools.

Referring particularly to FIGS. 1 and 3, ferrule 10 is located outwardly from strip S and is connected thereto via extension 1. A series of transverse holes 14 are formed in a portion of ferrule 10. Holes 14 constitute gripping means to grip the braided outer conductor 6 of wire A when a connector is crimped, as well as breaking down the oxide coating between ferrule 10 and braid 6 to provide an excellent electrical connection. Holes 14 further constitute inspection means so that the operator may readily view the braid before and after crimping. Holes can, of course. be located in ferrule 8.

Referring still to FIGS. 1 and 3, inner ferrule 8 is connected to ferrule 10 via strap 12 so that ferrule 10 and ferrule 8 are cocked relative to one another in a .manner that rearward end 8" of ferrule 8 is directed slightly downwardly. This arrangement provides a region 9 of easy access defining lead-in means whereby the braid 6 may be pushed over ferrule 8 without becoming snagged on the connector. The radiused edge 16 on ferrule 10 and the radiused edge 18.011 ferrule 8 provide further lead-in means to prevent the braid from catching on the connector.

The strap of metal 12 integrally joining ferrule 8 to ferrule 10 further serves to stop the insertion travel of outer braid 6 into connector C. This arrangement assures that all connections are alike and that the braids of subsequent connections are located the same within their respective connectors.

In operation, FIGS. 2 and 4, a wire A is prepared by stripping a portion of braid 6 away and exposing the center conductor 2 and insulation 4. A connector C is pushed onto the wire with the inner ferrule 8 under the end of braid 6 and over the insulation 4 and conductor 2. The connector is properly positioned when the end of the .braid 6 abuts strap 12. A grounding wire B is prepared by exposing a short length of its conductor, whereafter it is insertably disposed in the region of access 9 directly over the braid 6. The connector is then crimped by a suitable crimping tool or machine. Upon crimping, the legs of ferrule 10 close around braid 6 and the conductor of wire B and compress them into intimate engagement with the connector C. Inner ferrule 8 serves as a support to receive radial crimping forces and prevent the forces from damaging the conductor 2 and insulation 4 under the connector C. This would be especially important in the case of crimping the connector to a coaxial cable so as not to disturb the characteristic impedance thereof. During crimping, the end 8' of ferrule 8 is forced upwardly in concentric alignment with ferrule 10. Strap 12 enables the ferrules to be centered relative to one another where ferrule 10 is crimped onto a braid around ferrule 8.

The free end of grounding wire B may then be terminated to an associate grounding means. It should be noted that more than one grounding wire B may be joined to a connector C, if desired. Alternatively, the shielded braid of two or more wires A may be connected in series by a running grounding wire B from one connector C to another.

It should be noted that connectors C, according to this invention, may be pre-insulated by covering the outer surface of ferrule 10 with a sheet of suitable insulation, e.g. plastic or the like. This would be desirable in cases wherein the braid 6 of a shielded wire A is covered by a thin sheet of insulation material. Another alternative is to post insulate a connection by sliding a plastic or other dielectric sleeve over a connector after it is crimped.

It will, therefore, be appreciated that the afore-mentioned and other desirable objects have been achieved; however, it should be emphasized that the particular embodiment of the invention, which is shown and described herein, is intended as merely illustrative and not as restrictive of the invention.

The invention is claimed in accordance with the following:

1. An electrical connector comprising a tubular inner ferrule, a U-shaped outer ferrule, and a strap connecting said ferrules together at one end maintaining said ferrules spaced from each other and said inner ferrule disposed at an angle relative to a longitudinal axis of said outer ferrule, said outer ferrule partially surrounding said inner ferrule.

2. An electrical connector according to claim 1 wherein one of said ferrules has holes disposed therein.

3. An electrical connector according to claim 1 wherein the other ends of said ferrules are radiused.

4. An electrical connector comprising:

an inner cylindrical ferrule and an outer U-shaped ferrule, said outer ferrule spaced from and surrounding said inner ferrule, said outer ferrule and said inner ferrule integrally connected to each other by a bridging strap so that said inner ferrule is tilted with respect to said outer ferrule to provide an access space between said ferrules, said strap defining stop means to limit the insertion travel of a conductor means whereby said connector may be precisely positioned relative to said conductor.

5. An electrical connector for connecting grounding wire means to shielding wire means surrounding and in sulated from center conductor comprising an inner cylindrical ferrule adapted to be disposed under a portion of the shielding wire means and around a section of the insulated center conductor, said inner ferrule being partially surrounded by an outer U-shaped ferrule, said outer ferrule disposed in spaced relationship to said inner ferrule and adapted to be crimped onto said inner ferrule with the shielding wire means and the grounding wire means sandwiched between said ferrules, said ferrules connected together at one end by an integral strap.

6. In an electrical connector for connecting grounding wire means to shielding wire means, an inner ferrule member adapted to be disposed under a portion of the shield of the shielding wire means, an outer U-shaped ferrule member partially surrounding said inner ferrule member and adapted to be disposed over the portion of the shielding wire means, said members connected to each other at one end by a strap maintaining said members spaced from each other to define lead-in means to easily receive the shielding wire means, and said outer ferrule member having inspection means to permit inspection of the disposition of the shielding wire means in said connector.

7. A connector according to claim 6 wherein one end of said inner ferrule is cocked downwardly away from said outer ferrule to define said lead-in means, and wherein the other ends of said ferrules are radiused to further define said lead-in means.

References Cited UNITED STATES PATENTS 3/1960 Ayne et al. 7/1969 Gillespie.

DARRELL L. CLAY, Primary Examiner 

